Not applicable.
The starting point in the history of particle accelerators can be taken as June, 1932, when J. D. Cockcroft and E. T. S. Walton first used electrostatically accelerated particles to disintegrate a nucleus. Shortly thereafter, E. O. Lawrence and M. S.Livingston demonstrated atom smashing with a new accelerator called the cyclotron, in which high particle energies are achieved by accelerating the particles across a single gap between a pair of electrodes situated in a magnetic field which turns the particles into circular orbits. See the following publications:
(1) J. D. Cockcroft, E. T. S. Walton, xe2x80x9cExperiments with High Velocity Ions. I. Further Developments in the Method of Obtaining High Velocity Positive Ionsxe2x80x9d, Proc. Roy. Soc., A, Vol. 136, p.619 (1932)
(2) E. O. Lawrence, M. S. Livingston, xe2x80x9cThe Production of High Speed Light Ions Without the Use of High Voltagesxe2x80x9d, Phys. Rev. Vol. 40, p. 19 (1932).
Since then, many accelerators have been built so that today, accelerators for producing high energetic charged particle beams can be placed into several broad categories, depending on the particle energy produced:
Very low energy (100 KeV)
Low energy (0.1 to 10 Mev)
Medium energy (10 to 200 MeV)
High energy (0.2 to 1 BeV)
Very high energy ( greater than 1 BeV)
Very low energy accelerators are predominantly used in X-ray generators for medical applications and in electron microscopes. Low energy accelerators are used by the electronics industry for doping semiconductors. Medium energy machines are applied to smashing atoms. High and the very high energy accelerators are used for the generation of subatomic particles in high energy physics.
The very-low and the low energy accelerators are mostly electrostatic machines which need a source of very high voltage to operate. Here, the maximum voltage is limited to 5 MV, and is determined by the breakdown of insulation materials in air. These two systems are quite large in size, with the low energy systems being typically of 4 to 8 meters in length and occupying large rooms. For medium energy accelerators exceeding 10 MeV, the principle of acceleration by induction is applied. Here the particles undergo frequent impulses of energy increase as they move between electrodes driven by RF (radio frequency) power in step with their motion. These so called xe2x80x9cinduction acceleratorsxe2x80x9d are usually circular and very large in size, with the particle orbit diameters being measured in kilometers. Some other medium energy machines, such as the betatron are used for the acceleration of electrons. They are also circular but very heavy because of the huge electromagnets used to produce an electric field by induction. See generally:
(3) D. W. Kerst, xe2x80x9cThe Acceleration of Electrons by Magnetic Inductionxe2x80x9d, Phys,. Rev., Vol 60, p 47 (1941)
(4) M. S. Livingston, xe2x80x9cThe Development of High Energy Acceleratorsxe2x80x9d, Dover Publications (New York, 1966).
The semiconductor industry is a very large and important one in the US and in many other countries. Here particle accelerators of the very low and the low energy categories are used. However, their applications are very much restricted due to their size, weight and cost. Of the two types, electron beam accelerators are used for microelectronic circuit pattern generation on mask substrates. The other, the ion beam accelerators are used for the doping of semiconductors. These are rather peripheral uses of accelerator systems because the main xe2x80x9cworkhorsexe2x80x9d operation in semiconductor microcircuit fabrication is the projection, or transfer, of the electronic circuit patterns on mask onto the surfaces of semiconductor wafers. The workhorses of this semiconductor industry today are predicated upon optical beam systems because they are much cheaper, small in size and more reliable than current particle accelerator systems. However, current semiconductor technology is now approaching the xe2x80x9cdoor-stepxe2x80x9d of the limits of the capabilities of optical-based pattern-projection/transfer systems of excimer-laser-based optics. These systems produce light of wavelength near 150 nm, and since the fundamental optical resolution limit is the half-wavelength of light, this means that these optical systems will xe2x80x9crun outxe2x80x9d or become ineffective when industry moves, as essentially it must, down to 80 nm wide device structures. This limit is anticipated to be reached in about 5 years, that is around the year 2005. At the present time (year 2000) the smallest device dimensions in computer and memory semiconductor devices is at 180 nm. The 80 nm and smaller device dimensions will be needed to meet the future industrial requirements of faster circuits with increased number of transistors per circuit package. Therefore, for the semiconductor industry of the United States (which dominates and sets the world standards in this industry) to maintain its momentum of advancement, a new workhorse system needs to be developed. It was established some time ago (in the 1970""s) that such systems must be based on charged particle accelerators such as electron accelerators, proton accelerators and heavy-ion accelerators. However, current particle accelerator technology cannot meet these needs. Heretofore, the state-of-the-art accelerators have been nothing more than scaled down versions of the 50 to 70 year old technologies pioneered by van der Graaf and Cockroft and Walton. Major advances in this early technology have been limited mainly to the construction of the associated electronics and have involved the replacement of vacuum-tube-based circuits with semiconductors-based ones. A compact accelerator as opposed to the relatively immense accelerator sizes of earlier technology will be required to fulfill this forthcoming need for a new type of workhorse in the semiconductor industry.
In 1997, Kulish, Kosel and Kailyuk proposed a new principle for the acceleration of charged particles and formation of quasi-neutral plasma beams. With this new technical approach to particle accelerators, the use of EH-undulated fields was proposed wherein both negative and positive charged particles could be accelerated simultaneously and unidirectionally. See generally the following publications:
(5) Victor V. Kulish, Peter B. Kosel, Alexander G. Kailyuk, xe2x80x9cNew Acceleration Principle of Charged Particles for Electronic Applicationsxe2x80x9d, The General Hierarchic Description, Int. J. Infrared and Millimeter Waves, Vol. 19, No. 1, p.33 (1998).
(6) Victor V. Kulish, Peter B. Kosel, Alexander G. Kailyuk, Ihor Gubanov xe2x80x9cNew Acceleration Principle of Charged Particles for Electronic Applicationsxe2x80x9d, Examples, Int. J. Infrared and Millimeter Waves, Vol. 19, No. 2, p 251 (1998).
The insight associated with this new approach earned a concomitant theory of hierarchic accelerations and waves. Their studies and, resultant theories hold promise for a new particle accelerator technology which looks to requisite compactness for applications not only with the semiconductor fabrication techniques of the future but in a wide range of new procedures and products.
Practical applications of this advanced technology now are called for.
The present invention is addressed to particle accelerator structures and systems and to methods for carrying out particle acceleration to achieve the formation of energized particle beams from within beam production spacial regions of constrained extent. A combination of distributed excitation currents of relatively higher (R.F.) frequencies joined with uniquely configured acceleration channel defining core assemblies achieves the requisite spacial constraints through a directional altering of particle accelerating pathways which are established with magnetic materials effective to carry required time-varying magnetic fields and to permit the formation of resultant electric fields. Turning or undulating particle trajectories or paths are achieved in one embodiment with the use of steering assemblies intercepting particle trajectories to directionally alter them from one discrete acceleration channel segment into another as the energized particle trajectory path courses under electric field impetus from an overall accelerator structure input to its output.
Achieving compact accelerator architectures, these directionally changing particle directing paths may course from one to another of a sequence of parallel linear path segments with intra-path steering assemblies, or may employ circularly polarized EH-accelerators with continuous spirally-shaped acceleration channels having associated spirally-structured steering assemblies. Such a spiraling path arrangement is developed in conjunction with radially directed magnetic field formations evolved in accordance with the mandates of the system. Another approach to achieving spirally accelerating particle trajectories or paths employs longitudinally directed magnetic fields evolved from a unique core structuring and field winding arrangement which performs in conjunction with a centrally disposed open acceleration channel within which a spiral particle trajectory is formed and progresses from an accelerator structure input to its output.
Steering assemblies employed with the inventive accelerator architecture in general are formed with magnetically responsive core structures which are combined with a magnetic flux source to impose a magnetic field before an accelerating particle path of energized particles to Impose a curvature to that path. In one embodiment, rare earth magnets are employed to derive this magnetic field. In other embodiments, the permanent magnet derived fields may be modulated with electromagnetically derived fields to, in effect, tune the turning procedure. In one steering assembly arrangement, the turning magnetic field is combined with an accelerating electric field which is uniquely generated to evoke a particle accelerative effect within a turning environment. An advantageous feature of these steering assemblies resides in the development of a xe2x80x9ccoolingxe2x80x9d effect with respect to energized particles within the particle path trajectory. This effect functions to refocus an accelerating energized particle beam within a turning procedure in a manner wherein those particles at higher energies and wider radial turning trajectories lose energy while those of shorter trajectories tend to gain energy to effect the focusing of the particle beam as it enters, is turned and returned to an accelerating channel.
Embodiments of the accelerator architecture will be seen to include sequences of mutually parallel linear acceleration stages formed in a single parallel arrangement or in cylindrical accelerator structures wherein an undulatory energized particle trajectory or path route is achieved in conjunction with steering assemblies. Multiple levels of these accelerator stage sequences are described with steering assemblies which may perform between the separated sequences or along each sequence of a given combination of sequences.
The accelerator architecture and methodologies also uniquely permit the common acceleration of particles of two different characteristics, for example, positive charge particles and negative charge particles which may progress along the same array of acceleration channels to emerge from the accelerator structure output as a composite beam of oppositely charged particles. With appropriate merger, this composite beam may then evolve a quasi-neutral or neutral beam output. Those neutral outputs have particular application to propulsion systems, as well as to a variety of industrial processes.
Where dual levels of accelerator stage sequences are employed in conjunction with steering assemblies, each such sequence of acceleration channel defined stages can be employed to evolve tandem or dual acceleration trajectories, for example, utilizing particles of opposite charge. The result is either a dual beam or composite beam output with an accelerator structure exhibiting little or dismissable transverse momentum or reaction due to particle path changes. In this regard, directionally induced forces will tend to cancel or mutually compensate.
Novel generic compact accelerators are now proposed which will produce charged particle beams with energies from a very low to the medium energy regimes. The maximum system lengths will be small (less than 3 meters) and no heavy electromagnets are involved. This compactness is achieved by folding the trajectory of the particle beam into a serpentine arrangement with the linear sections of the serpentine passing through magnetic material (ferrite) cylinders supplied with windings which are driven by RF currents. The compact nature of these accelerators will make it possible to arrange many of them into clusters (up to 10 to 200 units) into a small area to produce specialized equipment for the mass production of microelectronic circuits. This will assure maintenance of the momentum of advancement in the electronics industry. Overall, the relationship of this compact EH-accelerator to large high energy accelerators can be likened to the relationship of the small PC computer to the large mainframe computer.
In addition, the compact accelerators will fulfill other current industrial needs in the processing of materials and in the manufacture of microelectromechanical systems. In general, the invention also will provide novel and cost-effective applications in the production of:
(a) energetic anion and cation beams for etching and ion-milling in microelectronics and microelectromechanical device fabrication,
(b) high-energy electron and ion beams for micro-welding and surface modification of dielectric and semiconductor surfaces,
(c) high energy atomic beams for surface hardening of metals and alloys,
(d) energetic neutral plasma beams for deposition and growth of thin amorphous and polycrystalline dielectric and semiconductor films,
(e) monochromatic high energy electron and cation beam sources for very high energy accelerators,
(f) cooling of electron and charged particle beams for very high energy accelerators,
(g) high intensity short-wavelength x-ray beams for non-destructive examination of mechanical structures, and
(h) sterilized foodstuffs against bacterial and virus infections.
See the following publications:
(7) N. Taniguchi, xe2x80x9cEnergy-Beam Processing of Materials. Clarendon Press-Oxford (Oxford, 1989).
(8) K. A. Wright, xe2x80x9cHigh Energy Electron Beams for Radiation Applications,xe2x80x9d Chapter 16, pp 432-445, Introduction to Electron Beam Technology, R. Bakish, Editor, John Wiley and Sons (New York, 1962)
Other objects of the invention will, in part, be obvious and will, in part, appear hereinafter.
The invention, accordingly, comprises the method, apparatus and system possessing the construction, combination of elements, arrangement of parts and steps which are exemplified in the following detailed description.
For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawings.